Tailored phase separation in P3HT:PS blends for enhanced synaptic performance in organic electrochemical transistors

Abstract

Organic electrochemical transistors (OECTs) are operated by the activity of the channel layer due to ion injection of the electrolyte. Currently, they are widely used in sensors, flexible, and wearable applications. OECTs have the potential to simulate synaptic model neuromorphic computing because they possess memory capabilities to express different states and can also be utilized as reservoir computing (RC) systems. Traditionally, OECTs face challenges with low mobility and the rapid return of ions to the electrolyte in the off state, which affects their synaptic properties. The blended P3HT:PS film significantly outperformed the pristine P3HT film, exhibiting a five-fold increase in performance and a high µC* value of 95.74 F cm⁻¹ V⁻¹ s⁻¹. Its enhanced crystallinity contributed to sharper transfer curves and enhanced electrical properties. The film also demonstrated improved synaptic behavior, exhibiting a stronger paired-pulse facilitation (PPF) effect and delayed ion back diffusion. Long-term memory (LTM) retention reached 55.25 % after 1000 s, representing a 1.4-fold improvement over the pristine film (39.36 %). In RC tests, 4-bit sequences (1100 vs. 0011) yielded distinct change of excitatory postsynaptic current (ΔEPSC) values (−0.21 µA vs. −0.58 µA), confirming effective signal processing. These findings establish OECT-based devices as promising candidates for neuromorphic computing.